* Avoid abbreviations

* Sample code for AppBar.leading

* Add a test for OverflowBox/FractionallySizedBox

* Minor wording improvements in the text.

The words "note that" here don't really contribute to the flow.

* Created a variant of InheritedWidget specifically for Listenables

* Add more documentation per review comments

Bug #1: These didn't work with directional alignments, due to an error
in the types of the constructor arguments.

Bug #2: Pretty sure RenderSizedOverflowBox never worked at all. As
soon as I wrote a test for it, the test showed that there was a
fundamental bug in its performLayout method: it didn't set
parentUsesSize, but it immediately tried to use the child's size.

* Revert "Revert "make LocalHistoryRoute a proper super-mixin (#23382)" (#23430)"

This reverts commit 3bbb3082.

This relands the LocalHistoryRoute change. The analyzer bug has been fixed.

* mark dartdocs as flaky

This reverts commit a3e0b0ae.

This change broke the analyzer during the dartdoc step.

This re-lands 3c56e6c7 on top of a new Dart SDK that contains new mixin syntax fixes.

If the scroll is out of range for any reason (for instance, changing scroll physics or manually messing with scroll position), the spring simulation causes the scroll position to slingshot towards the end. Also, before this change, `end` was unused.

* enable lint prefer_void_to_null

* replace last Null by void

Behavior remains the same for multiline TextFields. This behavior already happens on iOS and Android, but not desktop. #23014

* Future<void> main

* Future<void>.delayed

* prefer_void_to_Null

* address review comments

* add onLongPressUp geasture which is fired when a long-press ends

Before this PR AndroidView's gestureRecognizers field was a list of
gesture recognizers. This was problematic as when the widget was rebuilt
with the same gesture recognizer instances we would try to re-join the
recognizers to a gesture arena team and crash (as a OneSeqeunceGestureRecognizer
team can only be set once).

With this change, we instead take a set of factories.
This allows AndroidView to create the gesture recognizers just before
adding them to the team, and thus be sure that they are only added once to a
team.

The factories are identified by the type of the object they create, this
allows AndroidView to know when it is given an equivalent set of gesture
recognizer factories, and do nothing in that case.

This reverts commit bf92d7f2.

* prefer_void_to_null in flutter_test

* fix CI

* Refactor AnimatedSwitcher

This is mostly just a little bit of cleanup with hopefully no semantic
changes, done to teach me how the code works so that I could fix a bug.

* Add debugging information to AnimatedSwitcher

* Fix AnimatedSwitcher to handle the case of back-to-back changes

Previously, if a child was replaced the very next frame after it was
added, we'd get confused because we tried to reverse the controller,
which causes us to remove the child from the going-away list, before
we had added the child to the list in the first place.

The fix is just to move the reverse to after the add.

This reverts commit 3c56e6c7.

It breaks the AOT build.

* first pass

* revert WidgetsBindingObserver

* disable prefer_mixin

* docs and more mixins

* newer engine; binding fixes

* upgrade dependencies

* fix test binding

* remove whitespace

* remove the obsolete `enableSuperMixins: true`

* upgrade dartdoc to 0.22.0

* temporarily use git version of dartdoc

* fix pub global activate syntax

* use dartdoc 0.23.0

* Refactor of cupertino/material/widgets app

* update docs 

* Update tests for const

This reverts commit 61cf946b.

* Make CupertinoApp and MaterialApp both use WidgetsApp for Navigator

* Make CupertinoApp and MaterialApp const constructors

* Make WidgetsApp routes aware

* Update tests

* Revert "Revert "Add RichText support to find.text" (#22046)"

This reverts commit 8e704219.

* Revert "Implement Double Tap Handling in TextField and Editable (#21264)"

This reverts commit 02e87334.

Thanks @NikoYuwono for getting this working! We appreciate your help!

* Implement Double Tap Handling in TextField and Editable

* Fix test broken by the change and add test for double tap

* Fix affected tests

* Remove unnecessary new

* Fix test

Add back screenshot extension that was temporarily disabled.

Add matchesReferenceImage matcher to test that the screenshot extension
generates equivalent images to InspectorService.instance.screenshot.

* enable lint unnecessary_new

* fix tests

* fix tests

* fix tests